Objectives: 1. Determine at what larval instar locomotor behavior becomes rhythmical and is controlled by the circadian clock. 2. A running-wheel/oviposition apparatus has been designed to measure the occurrence of locomotor activity and egg-laying under various environmental conditions. 3. The influence of the calling-song on locomotor activity of T. commodus female will be studied. Does calling act in the female as a 'social Zeitgeber' and synchronize her locomotor activity with the emission of the calling-song? 4. Determine the sensory pathways, over which temperature cycles reach the clock and entrain singing-activity. 5. The result that cautery of the pars has different effects on the three rhythms spermatophore formation, stridulation and locomotor activity led to the assumption that different cell groups within the pars serve as mediators between the pars and the effector organs. Microlesions within the pars intercerebralis will be made in the hope to affect the three rhythms separately.